They work pretty well with plastic fletching. Not so good with feathers. The slot isn’t wide enough. I modified mine to hold feathers, but it is still a battle. Feathers are not well behaved unless they are pinched in a clamp.
You also don’t have the ability to play with the fletching angle or number of feathers (3, or 4). It is what it is, and that’s it.
So if you can afford to get something else, with a clamp, I think you would be happier in the long run…